Question 417350
determine whether the line through P1(1,-2) and P2(4,-3) is parallel to the line through Q1(4,3) and Q2(7,4)

The slope of line passing through (x1,y1),(x2,y2) = (y2-y1)/(x2-x1)

P1(1,-2) and P2(4,-3)
m= (-3-(-2))/(4-1)
m=-1/3
...
line through Q1(4,3) and Q2(7,4)
m=(4-3)/(7-4)
m=1/3
The slopes are different so they are not parallel